1. Technical Field
The present invention relates to a charging member cleaning unit, a method of producing a charging member cleaning unit, a charging device, a process cartridge, and an image forming apparatus.
2. Related Art
In image forming apparatuses such as electrophotographic copying machines, laser beam printers, and electrostatic recording devices, where an electrophotographic method is used to generate a toner image on the surface of an image holding member, and then transfer that toner image to a transfer target such as a sheet of paper, a photoreceptor drum is used as the image holding member. A corotron member is positioned near the photoreceptor drum, and the electrical discharge from the corotron member is used to substantially uniformly charge the surface of the photoreceptor drum. However, when a corotron member is used, a high voltage of several kV is applied in order to charge the surface of the photoreceptor drum to a predetermined potential, and this corona discharge generates ozone, which can cause degradation of the rubber and/or the photoreceptor provided inside the image forming apparatus. Accordingly, in image forming apparatuses that use the type of corotron member described above, not only the materials and shapes of the members used inside the apparatus are selected with care, but the apparatus also are provided with an exhaust fan to expel the ozone from the apparatus and/or an auxiliary device that detoxifies the ozone contained within the exhaust gas.
Furthermore, in an apparatus provided with a corona discharge device such as a corotron member, dust or fixing oil or the like floating within the air inside the apparatus may contaminate the corotron wire, making substantially uniform charging of the photoreceptor drum impossible, and increasing the likelihood of image irregularities. In order to allow periodic cleaning of the corotron wire to prevent electrical discharge irregularities, a cleaning device or the like may be positioned on the corotron wire, so that the wire can be cleaned periodically. However, providing a cleaning device for the corotron wire amounts to the provision of an additional device, which is not only a problem in terms of space, but the inclusion of an additional device for a small photoreceptor drum or the like also increases the restrictions associated with designing the apparatus. In order to address these problems associated with the use of a corotron wire, the use of a charging member such as a charging roller, which is brought into contact with the photoreceptor drum to effect charging, is attracting considerable attention.
In devices that use a charging device such as this type of charging roller, substantially uniform charging of the photoreceptor surface is a requirement, but during operation, dirt (mainly the toner external additives) gradually adheres to and accumulates on the surface of the charging member, and this adhered dirt can cause variations in the electrical resistance and the surface state of the charging member, thereby inhibiting substantially uniform charging. In order to prevent this soiling caused by external additives and the like, and enable a favorable image to be maintained over a long period of time, various charging member cleaning units are being tested for cleaning the charging roller.